1. Field of the Invention
The present invention relates to a gas turbine plant. Especially, the present invention relates to a gas turbine plant with a monitoring unit to monitor temperature in a turbine outlet and to detect an extraordinary state of the gas turbine plant.
2. Description of the Related Art
FIG. 1 shows an example of a conventional gas turbine plant. The gas turbine plant shown in FIG. 7 is comprised of a compressor 101, a gas turbine section 102, a combustion section 103 and a power generator 104. External air is taken in by the compressor 101, and is compressed, and supplied to the combustion section as compression air 105. Fuel 106 is supplied to the combustion section 103. The combustion section 103 combusts the fuel 106 using the compression air 105 to form the combustion air 110. The combustion air 110 is discharged from an exhaust section 112 as exhaust gas 111 after driving the turbine section 102.
N temperature detectors (N is a positive integer) 113 are provided in the exhaust section 112 in the neighborhood of an outlet of the gas turbine section 102. The N temperature detectors 113 are on N positions of the circumference of the exhaust section 112 in a constant interval. The N temperature detectors 113 monitor and measure the temperatures T1 to Tn on N positions in the neighborhood of the turbine outlet of the gas turbine section 102, i.e., blade path temperatures. The measured temperatures T1 to Tn are supplied to a monitoring unit 115. The monitoring unit 115 compares each of the temperatures T1 to Tn and a predetermined target value. The monitoring unit 115 detects an extraordinary state of the gas turbine plant when the difference of each of the temperatures T1 to Tn and a predetermined target value is equal to or larger than a tolerable level and emits a warning signal.
However, the temperatures T1 to Tn in the neighborhood of the turbine outlet change even when the gas turbine plant is operating normally. When the output of the gas turbine plant changes, swirler phenomenon is caused. As a result, the combustion gas 110 outputted from the combustion section 103 passes through the turbine section 102 in a twisted state. When the combustion gas 110 is twisted, the blade path temperatures T1 to Tn change. Such changes of the blade path temperatures T1 to Tn are not caused due to the extraordinary state of the combustion section 103.
Therefore, it is not possible to improve a detection sensitivity of the extraordinary state of the combustion section 103 by decreasing the tolerable level of the difference between each of the temperatures T1 to Tn and the predetermined target value, if the changes of the blade path temperatures T1 to Tn are considered.
In conjunction with the above description, a steam monitoring system in a steam cooled type gas turbine is disclosed in Japanese Laid Open Patent Application (JP-P2000-18050A). In this reference, cooling steam is supplied to a cooling object such as a combusting unit and winds. A temperature detector detects an exit temperature of the cooling steam after the cooling. A control apparatus inputs a detection signal from the temperature detector, and compares the detection signal with a predetermined signal. Also, the control apparatus generates a warning signal, a signal for adjusting an opening degree of a fuel flow rate adjusting valve or closing a closing valve, when the detection signal exceeds a predetermined signal.